Dextran is a complex, branched glucan, i.e. a polysaccharide made of glucose units, composed of chains of varying lengths typically from one or few thousand Dalton (Da) up to several hundred thousand Da.
The straight chain of dextran consists of α-1,6 glycosidic linkages between glucose units, while branches begin, usually, from α-1,3 linkages. Dextran is synthesized from sucrose by certain lactic acid bacteria, such as Leuconostoc mesenteroides, Streptococcus mutans and Lactobacillus brevis. 
Dextran sulfate is a polyanionic derivative of dextran, in which some of the C2-C4 and end group C1 and C6 positions are sulfated. Dextran sulfate has been known for decades and particularly as a potential substitute for heparin in anticoagulant therapy.
Dextran sulfate molecules are available in different molecular weights, different levels of branching and different sulfate contents and sulfation patterns. These physical and chemical differences among dextran sulfate molecules give rise to different biological and toxic effects.
There is a need for a dextran sulfate having improved biological effects while still not being toxic at pharmaceutically relevant dosages.